Differential expression profile of miRNAs in porcine muscle and adipose tissue during development.

MicroRNAs (miRNAs) are a class of non-coding RNAs that play a crucial regulatory role in many biological processes. Previous studies have reported miRNAs that are associated with the growth, differentiation, and proliferation of myocytes and adipocytes in pigs. However, differences in the miRNA expression profiles between muscle and adipose tissues during porcine development are unknown. Muscle and adipose tissues are the two major organs that are crucial for dynamic energy balance in the development and metabolism. Identification of differential expression profile of miRNAs will be useful for understanding the regulatory role of miRNAs in growth, development and evolution of these two tissues, and the research results will provide theoretical basis to improve meat quality. Therefore, we applied Hiseq sequencing to profile miRNAs in muscle and adipose tissues during four development stage at 1, 30, 90 and 240-day-old to explore their regulatory patterns at critical growth stages of pigs. We slaughtered 6 pigs at each developmental stages (24 pigs in total), respectively, RNA of three individual pigs were pooled and duplicate samples at each time point were given to sequence. We obtained a total of 96 million clean reads, and identified 329 known miRNAs and 157 novel miRNAs from all the libraries. We detected 37 miRNAs that were differentially expressed between porcine muscle and adipose tissues; 17 miRNAs which differentially expressed at 30, 90 and 240-day-old were considered as core differentially expressed miRNAs, among them, three miRNAs (ssc-miR-128, -133a-5p, -489) were differentially expressed at all four stages. KEGG analysis revealed the target genes of 17 core differentially expressed miRNAs were involved in 27 significantly enriched pathways (P<0.01), including the MAPK, Wnt, TGF-beta, and Notch signaling pathways, which are known to regulate myogenesis or are related to lipogenesis. 8 and 11 miRNAs were differentially expressed in the muscle and adipose tissues, respectively, of 30, 90, and 240-day-old pigs compared with the tissues of 1-day-old pigs. We selected five miRNAs from 17 core differentially expressed miRNAs to validate the miRNA-seq results by RT-qPCR, the RT-qPCR expression results corresponded well with those from the miRNA-seq. This study analyzed differential expression miRNA profiles between porcine skeletal muscle and adipose tissues during development, and provided valuable information to investigate the regulation mechanism of functional miRNAs.